Born in Sanremo, Liguria, she received her degree in Economics in 1969. From 1989 onwards, Bresso was a member of the provincial, regional and national party executives of the Democrats of the Left. 1995–2004, she was the President of the Turin Province, and, a Member of Regional Council (1985–1995) and of the Regional Executive (1994–1995) with responsibility for regional planning in Piedmont. She was a member of the Committee of the Regions and its Bureau 1998–2004. Between 2005 and 2010, she was President of the Piedmont region.
Since 2002, she is the Italian Vice-Chairperson of AICCRE; 2000–2004, she was Chairperson of the World Federation of United Cities, and, 2004–2005, founding Chairperson of the Organisation Cités et Gouvernements locaux Unis.
Between March 2005 and October 2008, she was President of the Union of European Federalists (UEF).